Rotary mowers and reel mowers are the two general types of turf mowers. Rotary mowers are generally used in high volume cutting environments and provide a rough cutting of the turf. When a more precise, finished cut is required, generally reel mowers are utilized. While the present invention relates primarily to reel mowers, those skilled in the art will recognize that the present invention may be useful in other styles of mowers as well. Therefore, while the preferred embodiment and examples will focus on reel mowers, the present invention should not be construed as so limited.
In a reel mower, there are one or more reels which rotate about a horizontal axis. The reel(s) operates in conjunction with a relatively stationary bedknife to shear off the grass blades. Generally, to maintain consistent quality of cut and to optimize the "clip" of the cut turf, the reel should be rotated more quickly with increasing ground speed. As used herein, the rotation of the reel will be referred to "reel speed." For a more detailed description of controlling reel speed in response to ground speed and to optimize the clip of the cut turf, reference may be had to the commonly assigned application titled Electronic Control for Turf Maintenance Vehicle, filed Jan. 3, 1992 (U.S. application Ser. No. 07/816,816) which is hereby incorporated herein by reference.
Typically, commercial reel mowers may be operated at certain top end or maximum ground speeds during transport (reels up). In the course of mowing, transporting the mower between areas to be cut, etc, operators need to have the maximum amount of control over ground speed. On the other hand, if the ground speed is too fast during mowing operations, the "clip" can become excessive (i.e., it degrades) and the cut turf can take on a poor appearance. That is, typically commercial turf mowers are designed so that they can travel at a ground speed greater than the preferred maximum mowing speed.
Therefore, supervisors prefer that operators mow at a ground speed less than the maximum possible speed of the mower. Also, the preferred mowing speed depends on the skill and experience level of the operator. For example, an experienced operator would know precisely when to raise and lower the cutting reel at the edge of a fairway when doing cross cutting, and therefore the more experienced operator may be capable of mowing at a faster ground speed. In fact, a supervisor might even want to establish a maximum mowing speed which is lower than the maximum "quality" mowing speed (i.e. the maximum speed possible while still maintaining an acceptable "clip").
It is a common perception, however, that slower mowing-improves the final appearance of the turf. As noted in the Lonn et al application referenced above, there is generally a relationship between reel speed and ground speed which provides for optimized clip. Further, the luxury of cutting the turf slowly is usually not available since large amounts of turf are generally required to be cut in the least amount of time possible (in order to reduce the cost of maintaining the turf and maximizing play, among other factors) and to maximize the time that other activities can utilize the turf being maintained.
Accordingly, the maximum mowing speed at which a mower can travel while maintaining acceptable performance is important to establish. At speeds above the maximum mowing speed the cut turf takes on a poor appearance (e.g., the proper reel speed may not be possible and so the clip degrades), the speed may cause improper operation of the cutting units themselves (e.g., such as by bouncing over rough terrain), and the speed may cause a greater wear on the mower itself leading to more frequent mechanical breakdowns.
The prior art includes simple supervisor lock outs on vehicles. Such "lock outs" simply establish a maximum ground speed achievable by the vehicle. For example, some vehicles will lock out certain gears of a transmission (e.g., the top gear) by use of a keyed switch. Of course, there are also simple engine governors which limit the RPMs of an engine, thereby limiting the ground speed of a vehicle. However, each of these devices suffers from the drawback that maximum control and speed of the vehicle is altered.
Therefore, there is a need for a supervisor switch which does not affect the maximum ground speed of the mower. Further, such supervisor switch should establish a maximum mowing speed of the mower by disabling the reels if and when an operator exceeds a certain preselected ground speed.